Method of preparing aluminum sulfate.



H; P. D. SGHWAHN.

METHOD 0? PREPARING ALUMINUM SULFATE.

APPLICATION FILED SEPT.16, 1912.

7 1,077,309. Patented Nov. 4, 1913.

WITNESSES. INVENTOR' I HEINRICH"F.I"D. sona -armor BnIiLEvIL'LE, ILLINOIS.

MEEHOD OF PREPARING ALUMINUM'SULFATE.

imzeoe.

Specification of Letterslatent.

' Patent-ed Nov. 4,] 913.

Application filed September 16, 1912 Serial No.- 720,-541. I

Td'all'eoiiom it may concern:

Be it known that I, Hnnviuon F. D. SGHWAHN, a citizen of the United-States, residing-at the city of Belleville, in-the county of st. Clair and State of Illinois, have invented a -certain new and useful Method of. PreparingnAluminum Sulfate, of which the following description is so full, clear, and exact as to enable those skilled in theartto which it appertains to use the -same,.refcrence being had to the accompanyingdrawings, forming part of this speci'li: cation,vin which the figure is a vertical section; partly in elevation, show-in; one form of apparatus for carrying outmy method.-

. This invention-is an improved method of treating clays, shales or other aluminous materials, ores or compounds and minerals for the more economical production-therefrom of aluminum-sulfate and in turn alu minum.

In my Letters Patent No. 759,927, dated Feb'r, 23, 1904, process, of preparing aluminum sulfate, I describe and claim a process for'treating clays, shales or other alu minous compounds for their purification with hydrochloric acid, and the production therefrom of aluminum sulfate with a sulfuric acid solution; and sinmltancously injecting heated air into the resultant: mixture of said-solution and aluminous materials, and this is not herein claimed.

This process just. referred to. like any other process now in vogue for the production of aluminum sulfate, requires the ready made sulfuric acid, andconsequently necessitates a great outlay for an acid plant, or to secure the acid in the open market, a very expensive and uncertain source, for obvious reason. 7

Now, it is known that sulfurous anhydrid (S0 when brought in contact in presence of air' and moisture with clays, shalcsor other aluminous ores, will dissolve therefrom in time the 'aluminumcontent and produce aluminum sulfate. And I am aware that such a process was for some time heretofore practised but required too much time, about: three months and more. And furthermore the. iron present in the ore, and on account; of these diszulvantas'es the process was aha-ndoned long ago.

To overcome these ditliculties above referred to and offer a cheaper and more rapid process for the production of aluminum sul product contained all the fate suhstantiall free of iron and in one operation, with the rapid production of sulfuric acid, is'the object of this invention. And I wish to heundcrstood here and in my claims that 'I mean under aluminous materials, any aluminous compound or ore, shales and clays, the silicates and hydrates or oxid of aluminum, or any other mineral or rock with an aluminum content, which always contain,

well known, more or iron, and thereby containi iating the sulfate prodluced thereof; and to separate the iron therefrom completely I use ozone or ozonized air in the manner as hereinafter described, an essenrial feature of this improvement, and of which it forms apart.

According to this my improved method the raw ore, such as for instance kaolinite or bauxite; or calcined ores, such as for instance kaolin, or shah are pmvdcred to pass through about 30-40 mesh screen, and I charge, after moistcniug' it with water, to become quite wet, into a suitable container or containers more fully described below. And upon the moist pulp I charge then in any suitable way sulfurous auhydrid gas (S0 suitably resultant from burning pyritcs or ln-unstone,1n a burner as usually used in the manufacture of sulfuric acid, or secure sald $40,, fromany othtr source, such as indus'- trial operations. However, this sulfurous anhvdrid gas is mixed generally with more or, less air, the proportion of which can in most cases be regulated by the operator, especially so inthe pyrites hurncrsj New, for reason that the oxygen in this air shall become more active as an oxidizing agent, or carricr for oxygen, the above mixture of gases, for an example, from said burners, is subjected to electrical discharges, in other words the air content of the burner cases is ozonized, preferal'ilv on enter-in s, the respective container or containers, to actat once in the improved condition in conjunction with the anhydrid' (S0,) in presence of moisture upon the pulp of the aluminous material and produce sulfates of aluminum and iron content, which latter is t-iausfmuicd in turn to a basic ferric salt by the action of the ozonized oxygen-of the air,

and forms a yellow mud, which on dissolvinr. and'decan'ting or filtering the product will settle or-remain with the waste pulp or residue,-and produce a pure solution'of aluminum sulfate.

1 In carrying out my method in the pre ferred form, I prefe ably use a series of con tainers, so as to ma ice a continuous operation of the other parts of the plant possible, and construct thein in size accordingly; And I provide these containers, each,- with the usual, perforated and acid resisting false bottom upon which the pulp is charged. While the gases from the pyrites burners, naming them as an example for the source of the mixture of sul't'urous anhydrid and air, is led by means of'a line into a certain loaded container, suitably under its false bottom. And said flue is provided, preferably, on or near its outlet into the con tainer, with a number of electric terminals or brushes as usually used for ozoning air within an electric circuit, and use this means for the discharge of electrical spar rs into and through the burner gases, and

ozonizing its oxygen content which in turn acts then in presence of moisture upon the sulturous anhydrid and produces sulfuric acid (II SO which in its nascent condition acts then most violently on the moist pulp of aluminous material, thereby rapidly dissolving the aluminum content of the mineral with the production of sulfate of aluminum therefrom, approximately of the formula ltl (fii() urthermore, the containe1-s.ai.e. substantially closed during operation and suitably connected tt'ronrnear their tops, by In ans oi tubes or pipes with a wooden stack to create a. certain draft between the container and burner, and move thereby the reagent gases more readily through the pulp, and in addition to this act as an acid tower in the usual way for the recovery of such sulfuric acid vapors which may have passed avay with the waste nitrogen from the air in the burner gases.

For the better understanding of the op eration of such containers with its accessories I have shown in the drawingsuclr combination of ap 'mratus suitable for my purposes, and in which 1 shows a. preferred form of apparatus, though other types may be used, 2 represents the container of the ore with the false bottom 3, preferably arranged in form of a step by means oi the. arches 4;, made of refractory material. and tiles covering: their tops. whi h protrude li rom one step over the other horizontally, leaving by means of their supports, only partly indicated the spaces 5 as perforations or pas ages between said art-hes l permitting thereby the gases aecumulatin; in chamber 6 l'roni the canal 7. dust chamher 5 and i) \'l'lltll-lHll'lltl' 9 respectively, to enter into the charge 10 and permeate the same tor the coi'iveri-ing ot' the ahnninous material into a sulfate. Said canal 7'is provided with the usual indiution brushes 1. which in turn are connected with an induction roil (not shown), and by means of which electrical discharges are made assist in creatinga dratt upon upon and through the passing gases from the burner 9 before entering into chamber 6, for the ozoniziug of their contained oxygen. [in opening 12 is provided for the charging of the ore, and this opening is normally closed by the cover or cap 13, while the doors it, and H" are provided for discharg in of the resultant sulfate.

1.? is a passage for the spent acid vapors and other gases, makingconnection will the acid-tower 16, by means of pipe I... Said acid-tower may be suitably arranged by filling it with pebbles or hard coke. or arranging it otherwise in the usual way for the recovery and concentration. of the spent sulfuric acid by the trickling of water or weak sulfuric acid over said coke by means of a spray 18, as usually 'u-actised.

19 is a' gate yn'ovided for the char of air into the canal T to mix the can from the dust-chamber 8 or burner 9 res-pee tively, in case a greater amount of ozone, to act upon the aluminous material, is d.esirable. And 520 is a steanrpipe for the charging" of steam into chamber 6 to moisten the gasesin' ease the aluminous ore was charged dry, or nearly so, as will be the case in treating plastic clays.

521. represents a pipe extending from the tower it to carry olt theavaste gases and i the entire combination of apparatus.- The (itiStHliiUilher 8 is provided for the depositing ot' the unburned pyrites. arsenic,antimony or zinc and iron oxid, etc but in case oi using brina-ztone for the'soaree of sulfur the dust chamber may be omitted.

In starting the apparatus for opera In the same is heated suitably by means oi? burning" fuel in the burner 9 and chamber t and to such an extent that watery rapt 0., steam will not condense cold ore charged into the container L, when the bu in"; of the pyrite-s or brimstone. as the ea. may be, will then be started at once, and the. heating of the apparatus disermlinued In heating the a maratus the opening; may answer for an outlet for the prodne of combustion, while no extra hez'rting is required in a continuous operation, for reason that sullicient heat is generated from the resultant reactions to carry on the method, as a continuous process.

In operating these. containers aeemidingg to my improved method the raw, or rat eined aluminous material, is first ground, it necessary. to pass through a thirty or i'orty mesh screen. The resultant ground i; terial may then be saturated with water or with some ohthe recovered weak a id from the towers or stacks,

one is charged into the contaim-rs in a laye 't'roin one to two teet thirir. when the ioadwi eouiainer is closed and w e with the ozonized burner gases no niurons anhydrid and ozonized or active oxygen from the air incidentally present in sa'id burner gases or purposely charged with the same. Soon the aluminous material will become hot and a more or less violent reaction will then take place, andthe mass swells and emits steam, and the time required for the finishing of the process depends-entirely on the volume of the reagent gases charged during a certain time, and the bulk of the pulp. But when the reaction ceases, the

swelling of the mass will cease also and cool on removing from the container, when it is ready for theleaching' out of the produced aluminum sulfate, which I preferably carry out by boiling the mass with water, while injecting ozonized oxygen or air into the boiling mass, and this has the object to connect by oxidation any. ferrous sulfate present into the basic ferric salt which separates on decantin a yellow mud, from the clear, then iron free sulfate solution,

upon the waste parts of the pulp Wh'icln forms a residue with other oxidized foreignmatters, which have been precipitated from the solution of aluminum sulfate. And after-drawing the iron free and otherwise pure solution of sulfate of aluminum from the waste or residue matter I preferably leach the same with water to recover its contained sulfate and use the resultant weal: solution for another boil of crude sulfate, while the strong sulfate solution is concentrated in the usual way by evaporation to become a marketable product. But at this point or preferably at a somewhat higher concentration, if the sulfate shall be used for the manufacture of aluminum, I add some carbon containing substances, such as for instance yellow pine saw-dust, ground corn-cobs, wood-pulp or any other carbonaceous or carbon containing substance of a porous nature or apt to evolve. carbon gases and combine their carbon with the sulfate on heating and forn'i a resistance conductor to electric currents, thereby avoiding a calcination of the sulfatc'ol aluminum for the production of the metal thereof, according:- to my improved process No. 964566, of July 19, 1,910.

Although I have specified the application of czonized air in combination with sulfurous anhydrid this will include also .imonizcd oxygen from other sources, and its use for the treatment of the aluminum sulfate solution resultant from this process for the precipitation of their contained iron per unit to produce an absolute iron free sulfate from sulfate solutions containing the same, which heretofore was not possible, And. the function of the ozone from oxygen or from oxygen in the air are further distinguished, however, from other oxidizing agents that it acts to accelerate the reactions in this process to a very marked degree by oxidizmg, so to say, ins'tautlythe S0, to H 80, right upon the moistore particles which it permeates and' heats, and consequently the time required for the solution of the aluminum content is reduced *to a small fraction of "that he'rto'fore necessary, with the possibility of recoi ering'tl'ie spent sulfuric acid as a {by-product. And furthermore with the use of ozone fora-n oxidizing ageut none o'f rare/ t elements will enter the material under trea'tmen't, as will/be the case if nitrate o'f ,s'o'clium -'or potassium or per ma'ngan'a te of potassium 'has been or is used as an oxidizing agent for the precipitation of 'the iron content in aluminum sulfate solutions as usually practised. And consequently produce a purer aluminum sul; fate, and in turn a purer aluminum indirect'ly from silicates, etc, at a very low cost and a comparatively small investment. But this purification of the sulfate solution by ozone :or ozon-ized air may be omitted in 'case the ferrous sulfate in the sulfate of aluminum, when marketed, is not objectionable, or the aluminous material'under treatment is free of iron. Instead of moistening the powdered aluminous, material, steam, *atery vaporsor a water spray maybe brought in contact with the reagent. gases to furnish the necessary moisture, so that the reaction between .the sulfurous anhydrid and ozonized air can take place, and therefore moist air will have the same effect and may also be used by me.

Although I prefer to use the above described arrangement of containers for my operations, I do not confine myself to their exclusive use as any other mechanical device therefor suitable, such as for instance a rotating barrel, as generally used in chlo-- rinating precious metal ores, maybe used by me. And it should be understood from the foregoing that the sulfurous acid vapors produced in this process as an intermediary may be transformed into sulfuric acid Without coming in contact with the aluminous' materials when entering the acid-tower and passing over the multitude of moist surfaces of its pebble or coke content, which acts then upon the mixture of sulfurous anhydrid and ozone or ozonized air in the same way as the moist aluminous material and the resultant sulfuric acid is recovered as a by-product, which, however, will take place only on reloading of the container or from incidentally escaping sulfurous acid vapors during operation, and is not herein claimed, neither the production of sulfuric acid by electrical means.

1. The manufacture of aluminum sulfate which consists in the treating of aluminous materials With a combination of sulfurous an hyd-ri d and ozoni'zed oxygen in the presence of moisture, thus transforming the aluminum content of such material into a sulfate, substantially as described.

2, The inai'nifacturc of aluminum sulfate which consists in the treating of aluminous materials with a coml'iination of sulfurcus anhyflritl and ozonized air in the presence of moisture, thus transforming the aluminum content ot' such materials into a sulfate, substantially as described.

3. The method of preparing aluminum sulfate, which consists in treating suiti- *iently-Wet aluminous materials with sul furous anhyclri'tl and ozone or ozonized air thus transforming the aluminun'l content 0': those materials into a sulfate and the iron c mtent of such materials into a basic ferric salt, then lixiviating the resultant mass with \\'alei','a 1id then separating the dissolved aluminum sulfate, the basic ferric salt with other insoluble ingredients contained. in the aluminous materials remaining as a residue,

thus producing a pure aluminum sulfate.

4-. The herein-described method of preparing aluminum sulfate, which consists in treating sufiiciently Wet aluminous materials with sulfurous acid gas and ozone or ozonized air, thus transforming the aluminum' and iron content of said materials into sulfate and basic sulfate respectively, then 

